| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester fiber for an industrial material, comprising a resin obtained by using a polymerization catalyst except an antimony compound and a germanium compound, containing no foreign matter causing the reduction of the strength of the fiber, and hardly soiling a spinneret when spinning the resin, and suitable for a rubber-reinforcing use such as a tire cord and a V-belt. SOLUTION: This polyester fiber for the industrial material is obtained by polymerizing the polyester by using a catalyst satisfying specific parameters without using the antimony compound and the germanium compound, and forming the obtained polyester into the objective fiber: (1) an activity parameter(AP) satisfying the inequality AP(min)<T(min)×2 (AP is a time required for polymerizing a polyethylene terephthalate having 0.5 dlg-1 intrinsic viscosity by using a prescribed catalyst at 275 deg.C at 0.1 Torr reduced pressure degree; T is the AP by using antimony trioxide as the catalyst with the proviso that the proportion of the added antimony trioxide is 0.05 mol% expressed in terms of antimony atom based on the acid components in the formed polyethylene terephthalate); (2) a thermostability indicator (TD) satisfying the inequality TD<25 (%) (TD is the decreasing rate (%) of the intrinsic viscosity when inserting 1 g PET having 0.6 dlg-1 intrinsic viscosity in a glass test tube, vacuum-drying the resultant PET at 130 deg.C for 12 h, and melting the dried PET in nitrogen atmosphere at 300 deg.C for 2 h).
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